Vane pump with a notch provided at a suction port

Abstract

A vane pump includes: a suction port configured to guide working oil to a pump chambers; a discharge port configured to guide the working oil discharged from the pump chambers; and a notch formed from an opening edge portion of the suction port towards a reversing direction of a rotation direction of a rotor, wherein the pump chambers each communicates with the suction port through the notch during a course of the transition from the state, in which the pump chamber is in communication with the discharge port, to the state, in which the communication with the discharge port is shut off, as the rotor is rotated.

The invention claimed is: 
     
       1. A vane pump comprising:
 a rotor linked to a driving shaft; 
 a plurality of vanes mounted to the rotor so as to freely and radially reciprocate with respect to a rotation axis of the rotor as the rotor rotates; 
 a cam ring having an inner circumferential surface on which tip ends of the vanes slide as the rotor is rotated, a space between the cam ring and the rotor being divided by the plurality of vanes to form a plurality of pump chambers; and 
 a side member having:
 a suction port configured to guide a working fluid to the pump chambers; 
 a discharge port configured to guide the working fluid discharged from the pump chambers; and 
 a notch extending from an opening edge of the suction port in a reverse-rotation direction opposite to a rotation direction of the rotor, wherein 
 
 an outer peripheral surface of the rotor has a plurality of protrusions and a plurality of recesses that alternate with one another, each protrusion protruding radially outward with respect to the rotation axis of the rotor, 
 at a plane perpendicular to a rotation axis of the rotor, the cam ring has with respect to positions of the suction and discharge ports, a suction region and a discharge region, and a transition region from the discharge region to the suction region in the rotation direction so that each pump chamber successively passes through the discharge region, the transition region and the suction region as the rotor rotates, 
 a volume of each pump chamber increases while a center of said each pump chamber passes through the suction region and decreases while the center of said each pump chamber passes through the discharge region, and 
 each pump chamber is configured so that while the center of said each pump chamber passes through the transition region, said each pump chamber directly communicates with the discharge port and communicates with the suction port only through the notch. 
 
     
     
       2. The vane pump according to  claim 1 , wherein
 the cam ring has a first center angle formed by the pair of the vanes, a second center angle formed by a first line in a radial direction of the cam ring that passes through the opening edge of the suction port and a second line in the radial direction that passes through an opening edge of the discharge port, and a third center angle formed by the second line and a third line in the radial direction that passes through a tip of the notch, and 
 the first center angle is equal to or smaller than the second center angle, and the third center angle is smaller than the first center angle. 
 
     
     
       3. The vane pump according to  claim 1 , wherein
 the plurality of vanes are respectively provided at respective ones of the tip ends of the protrusions of the rotor, 
 the inner circumference surface of the cam ring has an ellipse shape having a major axis and a minor axis, viewed from the rotation axis of the rotor, and 
 a center of the transition region is provided at the minor axis so that in each pump chamber, a gap between the outer peripheral surface at a corresponding one of the plurality of protrusions of the rotor and the inner circumferential surface of the cam ring becomes minimum when the center of said each pump chamber overlaps the center of the transition region, and while the center of said each pump chamber is in the transition region, said each pump chamber directly communicates with the discharge port only through the gap. 
 
     
     
       4. A vane pump, comprising:
 a rotor linked to a driving shaft; 
 a plurality of vanes mounted in the rotor so as to freely and radially reciprocate with respect to a rotation axis of the rotor while the rotor rotates; 
 a cam ring having an inner circumferential surface on which tip ends of the vanes slide as the rotor is rotated, a space between the cam ring and the rotor being divided by the plurality of vanes to form a plurality of pump chambers; 
 a side member having: 
 a suction port configured to guide a working fluid to the pump chambers; 
 a discharge port configured to guide the working fluid discharged from the pump chambers; and 
 a notch extending from an opening edge of the suction port in a reverse-rotation direction opposite to a rotation direction of the rotor, wherein 
 at a plane perpendicular to a rotation axis of the rotor, the cam ring has with respect to positions of the suction and discharge ports, a suction region and a discharge region, and a transition region from the discharge region to the suction region in the rotation direction so that each pump chamber successively passes through the discharge region, the transition region and the suction region as the rotor rotates, 
 a volume of each pump chamber increases while a center of said each pump chamber passes through the suction region and decreases while the center of said each pump chamber passes through the discharge region, 
 each pump chamber is configured so that while the center of said each pump chamber passes through the transition region, said each pump chamber directly communicates with the discharge port and communicates with the suction port only through the notch, and 
 a center angle of the cam ring formed by the pair of the vanes is greater than a center angle of the cam ring formed by a line in a radial direction of the cam ring that passes through a tip of the notch and a line in the radial direction that passes through at an opening edge of the discharge port.